I cannot answer this from a nursing perspective. As a police officer, I stayed on nights for 18 years. I loved the autonomy - with no higher management around, we made our own decisions. Day shift rarely did anything without seeking managerial input. The only reason I finally went to days was because my body could no longer handle the weird hours.
However, since you are in a learning mode (correct?), you want to be exposed to all aspects of the job. I'm not sure which shift does surgery prep, but I know most of them return on day shift. That is something to think about. But, if you have 12 hour shifts, it could be that you are getting everything you need on night shift. In that case, you can simply think about your personal life and what works better for you.
Best of luck!